Caffeine drinks may contribute to obesity, suggests small study
sugar and caffeine may be contributing to our expanding waistlines,
according to new research that could prove damaging for the booming
energy drinks market.
Professor Elaine Rush from the Auckland University of Technology in New Zealand claims to have found that an energy drink containing sugar, added caffeine and guarana causes the body to convert sugar into fat more rapidly than lemonade.
"These results could have huge implications when you think about how much sugar and caffeine people consume these days, and the high rates of inactivity," Professor Rush said.
Lemonade and other sodas are already being blamed by consumer groups for their role in increasing childhood obesity as many have a high sugar content.
But energy drinks have previously been exempted from such attention as their caffeine content was thought to increase metabolism.
The new study is small and will need to be confirmed by further research. However it will need a close look by energy drinks makers, set to make sales of more than £1 billion (€1.46bn) in the UK this year, according to Mintel data.
For the study, the New Zealand team recruited 10 healthy women aged 18 to 22 from a range of ethnicities. The subjects fasted overnight and were randomly given either 250ml of an energy drink or lemonade on the first day and the alternative on the second day of testing.
Lemonade contains around the same amount of sugar as energy drinks and is also carbonated but it contains no caffeine unlike cola drinks.
The sugar in both drinks was absorbed rapidly into the bloodstream - within a minute, according to Professor Rush - but she warned that when caffeine is also present the sugar is more quickly converted to fat.
"Sugar is a simple carbohydrate and evidence from this study shows that, coupled with a large amount of caffeine, the body rapidly turns it into stored fat," said the researcher.
Coffee's impact on sugar metabolism is currently unclear. The beverage has been linked to a reduced risk of diabetes but it is not yet known whether this is down to the caffeine content or other compounds in coffee. Earlier research has shown that caffeine could upset the body's ability to metabolise sugar.
The energy drink tested by Rush's team contained 28g sucrose and 81mg caffeine per 250ml can, which is similar to the amount of sugar in soft drinks and caffeine in a brewed cup of coffee.
"Simple carbohydrates and caffeine were not such a large parts of our diet in the past. Inactive people have trouble burning off excess energy and this leads to weight gain."
The findings are supported by a recent UK study, which found that caffeine increased cyclists' absorption of carbohydrates from a sports drink. But for those consumers not doing much exercise, these carbohydrates will be turned into fat.
"These drinks are often marketed as energy-boosters and may be perceived as helpful for weight loss. This is misleading - they are a calorie-booster and may actually cause weight gain," added Professor Rush.
She noted that the study is limited by its small sample size and the fact that the subjects were all young women. But the results are important as this area has not been explored before, she said.
"There has been a great deal of research about sugar and obesity, but not the synergy between drinks and fat stores."
The study also raises questions about the effects of consuming high-sugar foods and highly caffeinated drinks together in a short period of time. Caffeine lasts in the body for four to six hours, so people who have caffeinated drinks, including sugar-free energy drinks or coffee, and then eat sugary food within this time frame, may experience similar effects.
"This area needs further research, as well as the long term effects of combined caffeine and sugar on sedentary people's health," added Professor Rush.
